This article is a place holder and needs someone to take it in hand and finish the first draft. If you would like to take this article in hand, leave a reply message below or contact Rock Currier via private message by clicking on the PM button next to my name at the top of the article.

Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?

Below are some preliminary notes I have made about Aurichalcite. This entry and thread has been made as a place holder for information that you will hopefully contribute about Aurichalcite. It should be in no way be thought of as a claim I have staked out to write about this mineral, and in fact is an invitation for someone to step forward and create the article about this mineral. If you are so inclined and have questions about the format that such an article should have, go the The welcome topic at the top of the Best Minerals forum and read what has been posted there. Also take a look at some of the more mature articles that have already been written like Rhodochrosite, Adamite, Millerite etc. You will need also to pick out other images of Aurichalcite that will go into the article.

Aurichalcite is a secondary copper mineral usually found in the oxidized portions of copper/zinc deposits. The mineral is found at many localities and grows in slender light blue crystals that are rarely if ever over one cm and most are much smaller. Good specimens are not common except if you are a micromounter and in that case they are plentiful. Radiating tufts and clusters of these small blue crystals often make for beautiful if very delicate specimens. If you have a good aurichalcite specimen you will be advised to keep it in a box where it can be protected from the normal dust that accumulates on ordinary household items. They should not be placed even in a display cabinet for long periods of time, as they are difficult to impossible to clean. Though it has been found at a fair number of localities it seems that each generation must find its own because they become dirty and are eventually thrown out. Aurichalcite and rosasite are dimorphs and they must be analyzed for copper and zinc to determine which is which. Aurichalcite tends to be a lighter blue color than rosasite.AurichalciteAustraliaNew South Wales, Broken Hill, ABH Consols Mine. “Beautiful specimens forming stalactitic masses, the centers of which contained dyscrasite, iodyrite and limonite, were found in a single vug in the ABH Consols mine.”11 The Minerals of Broken Hill, W.D. Birch et. al. 1982, p.81.

AurichalciteEnglandDerbyshire, Matlock Bath, Rutland Cavern. “…is one of the earliest known localities for aurichalcite or “cupreous calamine”1, and is the classical British locality. It forms pale green, felted or pearly crusts or tufts of blades up to 5 mm long, often associated with rosasite and hemimorphite and scattered on fluorite and calcite. Although attractive and having micromount potential, the specimens tend to be sparsely covered and do not compare with those from Mexico, Arizona or Iran.”2 Better specimens are said to come from Stafford, Ecton Hill in the same district.1 Tooke, 1837; Adam, 1845; Connel, 1848; Greg and Lettsom, 1858; Braithwaite and Ryback, 1963a. – 2 Mineralogical Record, Vol. 14, 1983, p20.

A quarry in upper devonian limestones, disseminated by lead, zinc and copper bearing veins, located 1.5 km NNE of Rohdenhaus, NW of Wülfrath. Aurichalcite is quite a common mineral in the quarry and very good specimens have been found over the years. Typically the Aurichalcite roses get up to about 0,5 cm in diameter and occasionally cabinet specimens have been found covered all over with Aurichalcite aggregates. Aurichalcite is usually accompanied by very nice Rosasite, Smithsonite and weathered Sphalerite.Following a fatal accident involving a mineral collector in 2008 the quarry management does not allow any mineral collecting in the quarry at least for the year 2009. In the future the management will review its point of view.

AurichalciteMexicoDurango, Mapimi, Ojuela Mine. Mapimi has produced some beautiful specimens but because the mineral is so delicate most of the specimens collected never reached collectors in an undamaged condition. The specimen shown below is in the Romero collection and somehow managed to survive. Mapimi produced at least one pocket of beautiful sky blue thin bladed calcite whose color was caused by included aurichalcite.11 Mineralogical Record, Vol. 18, 1987, p406.

AurichalciteNamibiaTsumeb. In the upper levels of the Tsumeb mine “aurichalcite crystals up to 1 cm on a white background of hydrozincite. Both are richly covered by small, transparent hemimorphite crystals.”11 Georg Gebhard, Tsumeb, 1999, p284.

AurichalciteArizona, Gila County, Banner District, Hayden. 79 Mine A & B & C & D & E. Perhaps the best specimens found to date are from the 79 mine near Hayden, Arizona. It is a common mineral in the mine but as usual the best specimens were collected from a pocket in 1971 which produced about ten flats of material of which about one flat was of truly superior quality. This material consists of crusts of sparkling turquoise green needle like crystals a little over a cm long and well terminated if you look closely. I hope their owners will keep them well packed away from household dust and dirt. What would be the price of these specimens today? For the better ones certainly more than $2000. How many of them have survived intact the twenty or so years since their discovery would be interesting to know. See Wendell Wilson’s good article in the Mineralogical Record.1 1 Mineralogical Record, Vol. 18, 1987, p 299.

AurichalciteArizona, Pinal County, Tiger. The copper mine at Tiger also produced some specimens, but nothing worth writing home about. See the picture in the image bank. These kinds of very delicate specimens need to be sealed away in good air tight containers to protect them from dust, dirty air and brushing up against other specimens or even the box they are kept in.

AurichalciteArizona, Pima County, Helvetia, Isle Royale Mine. “Bob Lane…an active Arizona field collector, was set up at the La Quinta with some very attractive rosasite and aurichalcite from the Isle Royale mine…It was a big strike, literally hundreds of flats, with many cabinet pieces recovered.”11 Mineralogical Record, Vol. 19, 1988, p210.

AurichalciteCalifornia, Inyo County, Darwin. “A very common mineral found in many of the mines (at Darwin) having a large amount of secondary zinc ore. Custer mine group: as excellent blue-green crystals from a small prospect tunnel opposite the Custer headframe. Defiance mine; found through the upper workings, mostly above the 400 level. Zinc Hill mine: collected from the upper workings as micro-crystals associated with hemimorphite.”11 Mineralogical Record, Vol. 15, 1984, p13.

AurichalciteMissouri, Granby. Would you believe that an old lead mine near Granby produced this specimen of aurichalcite crystals growing on calcite crystals?

AurichalciteNew Mexico, Socorro County, Magdalena District, Kelly Mine A & B. Aurichalcite has been found throughout the district, mostly as micro acicular crystals on matrix and fine-bladed aggregates, often with a silky appearance. It is sometimes found as layers between botryoidal and crustiform smithsonite, as drusy cavity linings and as small tufts on smithsonite and other minerals. “The peculiar feathery habit of crystallization makes the mineral troublesome to handle…The noteworthy feature of the occurrence is that the delicate plumose clusters of crystals are preserved by clear crystals of calcite…The single occurrence known in the Graphic mine is of indescribable beauty. A crystal grotto a dozen feet in diameter is entirely lined with exquisite and delicately tinted aurichalcite , which is again covered by a thin layer of calcite a quarter to half an inch in thickness, made up of perfectly and brightly faceted crystals closely grown together. Some of the showiest specimens obtained were four to five times the size of a man’s head.”11 Keyes, C.R., Zinc Carbonate Ores of the Magdalena Mountains, Mineralogical Magazine, Vol. 12, p109-114.

Not that I'm aware of. I always wanted a Kelly Mine Smithsonite and when I got one I was almost disappointed to see the rind of Aurichalcite under the smithsonite. Since then I've noted it on all such blue Smithsonites and Hemimorphites that I've come across.

I would actually have to disagree with you. Being a collector of New Mexico minerals, I have seen hundreds of specimens of "Kelly mine" smithsonite (there are actually several mines within the Magdalena District that produce the blue to blue-green smithsonite). Out of the many smithsonite specimens I have seen from the area, a majority of them do occur with aurichalcite, but I have seen quite a few specimens as well that have absolutely no aurichalcite association. I do agree that many times the aurichalcite enhances the color of the overlying smithsonite, but the smithsonite can also singularly display the gorgeous color we know as "Kelly Blue". It really just depends on the pocket or stope in which the specimens were collected.

Thanks Philip. You've seen far more than me. I still wonder if those blue specimens that don't exhibit any underlying Aurichalcite aren't coloured by microscopic included Aurichalcite. An EDS of a polished face or a thin section should tell the tale.

Rob, that's not a bad theory. I can ask Virgil Lueth (curator for the New Mexico Bureau of Mines Mineral Museum) next time I talk to him if he has done any research on this. If anybody would know, he would.

Rob,I have noticed that many of the blue smithsonites from the Hidden Treasure are on aurichalcite and have wondered if the smithsonite color came from the aurichalcite. All the other smithsonite from there is white. In the top photo I posted above the smithsonite is under the aurichalcite and it is white.

Philip Simmons Wrote:-------------------------------------------------------> Rob, that's not a bad theory. I can ask Virgil> Lueth (curator for the New Mexico Bureau of Mines> Mineral Museum) next time I talk to him if he has> done any research on this. If anybody would know,> he would.

Rob,

I talked to Virgil Lueth today and he was in support of the observations I posted earlier. He said they did microprobe analysis on several of the smithsonites and found no evidence of aurichalcite inclusions or concentrated areas of copper (which would be expected if the color was caused by aurichalcite) within the samples. The results showed a uniform presence of copper throughout the smithsonite crystal structure which suggests that the color is indeed caused by copper, and not by inclusions.

Thanks for your interest in the subject. I enjoy researching these types of questions to help others better understand the wonderful world of mineralogy.

Thanks Rick, Those are very nice specimens and the sort of thing that led me to think that the blue was from included aurichalcite.

Thanks very much Philip and please thank Virgil for me. Aurichalcite has such a distinctive colour I thought that if the Cu was replacing the Zn in Smithsonite and Hemimorphite they would show more variability in colour from white through to the Aurichalcite blue. Although I said an EDS would tell the tale, there is a remote possibility that the inclusions in the EDS homogeneous specimens are smaller than the cubic micron averaged over by the electron beam. That's probably grasping at straws but it does happen (e.g. with miargyrite inclusions in galena). Still probe homogeneous specimens are a very strong argument for Cu replacing Zn in the structures.

Looking back at Philip's earlier post I see:"there are actually several mines within the Magdalena District that produce the blue to blue-green smithsonite"This is probably the variability in colour which I have not yet seen and I would expect with Cu substitution. A little knowledge is a dangerous thing!!!

Rob, I'm glad I can come up with useful information. Many of the mines within the Magdalena District produced many variants of the "Kelly Smithsonite" rainging in color from sea-green to deep "Kelly" blue. If you want to see a piece of the sea-green smithsonite, take a look at picture 103918. Smithsonite from the district not only occurred as the classic blue specimens, but also as grey, white, brownish, green, canary yellow and colorless specimens.

Sorry for the rabbit trail, Rock. Maybe this info can be included in the Best of Smithsonite page whenever it gets started.

Thanks Philip. Prior to this thread, I would have blithely assumed that the colour of this photo was wrong, but that is not so.

Green Cu substituted Smithsonite

From this I suspect that the Cu probe homogeneous specimens range from slightly green to this colour and the same sort of colouring should be possible with Cu substituted Hemimorphite or Hydrozincite. I also suspect that the Aurichalcite blue specimens are in fact coloured by Aurichalcite. Could you please ask Virgil if his probe homogeneous specimens were this green or Aurichalcite blue.?

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